[SyntaxTree] Extend the syntax tree dump to also cover `NodeRole`

We should see `NodeRole` information in the dump because that exposes how the
accessors will behave.

Functional changes in the dump:
* Surround Leaf tokens with `'`
* Append `Node` dumps with `NodeRole` information, except for unknown roles
* Append marks to `Node` dumps, instead of prepending

Non-functional changes:
* `::dumpTokens(llvm::raw_ostream, ArrayRef<syntax::Token>, const
SourceManager &SM)` always received as parameter a `syntax::Token *`
pointing to `Leaf::token()`. Changed the function to
`dumpLeaf(llvm::raw_ostream, syntax::Leaf *, const SourceManager&)`
* `dumpTree` acted on a Node, rename to `dumpNode`

Differential Revision: https://reviews.llvm.org/D85330